Jimmy Lee Dykes, the man who held a 5-year-old boy hostage for nearly a week in an underground bunker in Alabama, had two homemade explosive devices on his property and engaged in a firefight with SWAT agents before they stormed the bunker and killed him, according to the FBI.

One explosive device was found inside the bunker and another was located in the PVC pipe negotiators used to communicate with Dykes, the FBI said Tuesday night. Both devices were "disrupted," according to the FBI.
The search for hazards is expected to continue through today.

Preliminary investigation reports indicate that Dykes engaged in a firefight with the SWAT agents who made entry, according to the FBI.

Officials were able to insert a high-tech camera into the 6-by-8-foot bunker to monitor Dykes' movements, and they became increasingly concerned that he might act out, a law enforcement source with direct knowledge of the case told ABC News Monday.

FBI special agents were positioned near the entrance of the bunker and negotiators were able to convince Dykes to approach the bunker door. FBI agents used two explosions to gain entry into the bunker. It also appears that Dykes reinforced the bunker against any attempted entry by law enforcement, according to the FBI.

ABC News has learned that Dykes first opened fired on the agents during the bunker raid. Moments later, the agents returned fire, killing Dykes.

The shooting review team continues to gather facts regarding the incident, the FBI said.

The boy, only identified as Ethan, was rescued from the scene by a waiting ambulance. The bunker raid came six days after Dykes boarded a school bus, fatally shot the driver and abducted the boy, who suffered no physical injuries.

"It's all about timing that is why you practice. You practice blowing the door in split seconds, flash bang, shoot before Mr. Dykes would even have an opportunity to react," Brad Garrett, former FBI agent and ABC News consultant, said.

Meanwhile, Ethan is set to celebrate his 6th birthday today, happily reunited with his family.

Ethan's thrilled relatives told "Good Morning America" Tuesday that he seemed "normal as a child could be" after what he went through and has been happily playing with his toy dinosaur.

"He's happy to be home," Ethan's great uncle Berlin Enfinger told "GMA." "He's very excited and he looks good."

"For the first time in almost a week, I woke up this morning to the most beautiful sight...my sweet boy. I can't describe how incredible it is to hold him again," Ethan's' mother wrote in a statement released by the FBI Tuesday.

Ethan is "running around the hospital room, putting sticky notes on everyone that was in there, eating a turkey sandwich and watching SpongeBob," Dale County Schools Superintendent Donny Bynum said at a news conference Tuesday.

When asked about a birthday party for Ethan, Bynum said, "We are still in the planning stages. Our time frame is that we are waiting for Ethan, waiting on that process, but we are going to have it at a school facility, most likely the football stadium at Dale County High School."

He said many "tears of celebration" were shed Monday night when Ethan was reunited with his family.

"If I could, I would do cartwheels all the way down the road," Ethan's aunt Debra Cook told "GMA." "I was ecstatic. Everything just seemed like it was so much clearer. You know, we had all been walking around in a fog and everyone was just excited. There's no words to put how we felt and how relieved we were."

Cook said that Ethan has not yet told them anything about what happened in the bunker and they know very little about Dykes.

What the family does know is that they are overjoyed to have their "little buddy" back.

"He's a special child, 90 miles per hour all the time," Cook said. "[He's] a very, very loving child. When he walks in the room, he just lights it up."